Get a sample of the old metal soffit. That will help with metal fabrication and with color match on sheet metal. A color metal color chip sample will assist if needed.
We use an in house metal brake, to fabricate the new metal soffit. If you can’t get a sample, EXCELLENT, if not then take great measurements. Sometimes it will take going to multiple supply houses to find the best metal coil for match. Once you got this you are almost home free.
Fabricate the metal to clip together, usually a U clip style going into the newly fabricated soffit. Lastly install, your new metal soffit.